From 79115bd199ce0112926e49ad2ba4df1e2666adcf Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Tue, 19 Jul 2022 10:53:06 +0200
Subject: [PATCH] Don't add duplicate frames.

---
 src/Avalonia.Base/PropertyStore/ValueStore.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Avalonia.Base/PropertyStore/ValueStore.cs b/src/Avalonia.Base/PropertyStore/ValueStore.cs
index 093235955e..a90bb4eb73 100644
--- a/src/Avalonia.Base/PropertyStore/ValueStore.cs
+++ b/src/Avalonia.Base/PropertyStore/ValueStore.cs
@@ -141,7 +141,6 @@ namespace Avalonia.PropertyStore
             {
                 var frame = GetOrCreateImmediateValueFrame(property, priority);
                 result = frame.AddValue(property, value);
-                InsertFrame(frame);
             }
 
             if (TryGetEffectiveValue(property, out var existing))
@@ -528,6 +527,7 @@ namespace Avalonia.PropertyStore
 
         private void InsertFrame(IValueFrame frame)
         {
+            Debug.Assert(!_frames.Contains(frame));
             var index = _frames.BinarySearch(frame, FrameInsertionComparer.Instance);
             if (index < 0)
                 index = ~index;